Multilayer thick film circuits have been used for many years to increase circuit functionality per unit of area. The dielectrics used in these circuits are comprised of finely divided particles of dielectric solids, dispersed in an inert organic medium, the dielectric solids being inorganic oxides or glasses. Recent advances in circuit technology include the requirements of higher circuit densities and higher propagation speeds. Dielectric materials having low dielectric constants that are stable at high temperatures and high humidities and that have good mechanical properties are required for such uses.
Vacuum has the lowest dielectric constant, which is 1.0. Polymeric dielectric materials typically have dielectric constants in the range of about 2.6 to about 3.8. Some of the problems associated with these polymeric materials include their inability to withstand high temperatures, their degradation under extended exposure to temperatures in excess of about 200.degree. C., poor thermal conductivity and poor resistance to humidity. Glass-ceramic materials are more stable than polymeric materials at high temperature and in humid atmosphere, and have better mechanical properties for most dielectric applications than such polymeric materials. However, glass-ceramic materials have higher dielectric constants than polymeric materials, typically in the range of about 7-12, and have thus far not been found to be acceptable for use as dielectrics in thick film circuits and the like.